This invention relates generally to tools and more particularly concerns improvements to radial arm saws. Radial arm saws have been in use for many years and have collected a xe2x80x9cbadxe2x80x9d reputation during this time. My first experience with this saw began in 1947 when I started employment in a large aircraft factory. I hired in as an automotive mechanic and our shop was next to the crating shop where the radial arm saw was located. During evening and midnight shifts the automobile mechanics crated the xe2x80x9cmust goxe2x80x9d shipments. The first day of work the foreman asked if I had used power saws, and I replied xe2x80x9cYes, the band saw and table saw.xe2x80x9d He said xe2x80x9cGood, but don""t use the radial arm saw. It""s too dangerous.xe2x80x9d Later the lead carpenter showed me how to use this saw. He cautioned me about sawing too fast on thin lumber (one inch or less). The saw teeth can dig into the board and walk across the board like a race car wheel, and the carriage will violently strike the outboard stops. Even if not injured, you will make every effort to avoid this dangerous situation in the future.
I worked in this area for nine years, and we had one accident on the radial arm saw. While the saw was running a small scrap board fell off a stack and slid into the saw. The blade rode up on top of the scrap and threw it out the back where it ricocheted off the fence and hit one of the carpenters on the arm. It made a small bruise but the man lost no time.
In contrast, during these nine years, three carpenters lost one or more fingers in the table saw.
Deservedly or not the radial saw arm still carries the xe2x80x9cbadxe2x80x9d reputation.
In 1981 I purchased a radial arm saw for my home shop and used it without incident until 1999. I was sawing 1xc3x9712""s. My blade wasn""t as sharp as it should have been, and one of the boards had a heavy grain running length wise. This combination, while trying to force the cut, caused the saw to climb atop the board and the carriage to strike the outboard stops.
One scare was enough. I decided then and there that I needed a hydraulic cylinder to control the feed speed on my radial arm saw. Thus, necessity is the mother of invention.
It is, therefore, an object of this invention to provide a device which causes travel of a radial arm saw carriage to cease when the operator releases the radial arm saw handle. Another object of this invention is to provide a device which causes travel of a radial arm saw carriage to cease if the operator ceases to pull the radial saw arm handle. A further object of this invention is to provide a device which reduces the possibility of a radial arm saw carriage inadvertently drifting or jumping from its return position due to accidental contact with scrap lumber.
It is therefore an object of this invention to provide a safety device for the radial arm saw consisting of a valve operated hydraulic cylinder. The spring loaded hydraulic metering valve in conjunction with the operating handle will stop the carriage at any time the handle is released or the operator stops applying a pulling motion on the handle.
The hydraulic cylinder will also keep the carriage in the return position once the operator has moved it there, no drifting, no jumping from accidental contact with scrap lumber.
The adjustable speed feed gives the operator more control of the sawing operation. Once adjusted the operator can apply extra pulling moment on the handle, and the carriage will never exceed the adjusted speed, thus preventing the dreaded kick forward and slamming of the outboard carriage stops.
In some shops the foreman may elect to adjust the feed to a safe speed and lock the adjustment at that position. Thus, the radial arm saw would be a safer and more productive tool.